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Beamline 3: Irradiance Calibrations

Description:

Beamline 3 is home to the Facility for Irradiance Calibration Using Synchrotrons (FICUS). FICUS takes advantage of the calculability of synchrotron radiation. The beamline is used to calibrate the absolute spectral irradiance of ultraviolet light sources like deuterium lamps.

Calibrated deuterium lamps are available through the NIST Calibration Program.

Beamline 3 was the basis of the NIST contribution to the Consultative Committee for Photometry (CCPR) key comparison K1.b.

Specifications / Capabilities:

Spectral range 200 nm to 400 nm

Table 1: Components of the Relative Uncertainty (k=2) of Spectral Irradiance of Synchrotron Radiation at the FICUS

Source of Uncertainty Nominal Value Relative Uncertainty Sensitivity Coefficient Uncertainty in Irradiance
Electron energy 380 MeV 0.02 % 0.057 0.0011 %
Beam current ≈15 mA 0.4 % 1 0.4 %
Orbital radius 837.077 mm 10-10 0.66 6.6 · 10-11
Window transmittance ≈0.8 0.5 % 1 0.5 %
Distance 6926 mm 0.086 % 0.015 0.17 %
Detector alignment   ±0.6 mm 0.0011 0.066 %
Aperture size 9.5 mm 6.5 % 0.015 0.096 %
Air absorption     1 0.24 %
Combined       0.72 %

 

Table 2: Components of the Relative Uncertainty (k=2) of Spectral Irradiance of Deuterium Lamp Calibration at the FICUS

Source of Uncertainty Nominal Value Relative Uncertainty Sensitivity Coefficient Uncertainty in Irradiance
SURF radiation     1 0.72 %
Wavelength    ±0.1 nm 0.013 0.27 %
Stray light and fluorescence     1 0.5 %
Lamp distance 300 mm 0.066 % 2 0.13 %
Lamp stability     1 0.5 %
Random uncertainty       0.6 %
Combined       1.2 %
SURF Beamline 3
<font color="#006400"><strong>Deuterium lamp (left) and undispersed synchrotron radiation (right) at beamline 3.</strong></font>
Contact

Name: Uwe Arp
Phone: 301-975-3233
Email: uwe.arp@nist.gov
Address:
100 Bureau Dr, MS 8410
Gaithersburg, MD 20899-8410


Name: Ping-Shine Shaw
Phone: 301-975-4416
Email: ping-shine.shaw@nist.gov